This invention relates to dental apparatus, and more particularly to a dental instrument for measuring the size of a tooth and for placement of a dental bracket at an exact site location on the tooth based upon such measurement.
One of the methods of orthodontic correction is the placement of brackets on successive dental surfaces with the connection of an arch wire between the brackets. In the direct method placement, the bracket is directly secured onto a dental surface and the wires appropriately interconnected to provide the necessary torque and angulation in order to orthodontically correct the positioning of the teeth.
One of the skills of an orthodontist is to determine the appropriate position for the placement of the brackets. There are numerous recommendations as to appropriate positioning of the brackets. Some suggest that the arch wire should be constructed along the middle of the clinical crown. Others suggest placing straight guidelines parallel to the long axis of the clinical crown and then moving the bracket up and down until the middle of the slot base is at the same height as the long axis point. Some simply recommend that the bracket heights be determined according to the size and shape of the teeth without specifying an exact position. Nevertheless, at the heart of every excellent treatment result, there lies a well placed appliance.
One of the more recent recommendations is to place the bracket along the long axis of the tooth which extends from the gingival margin to the incisal edge or cusp tip. Along this axis, the suggestion is to utilize the mid point of the vertical long axis of the clinical crown.
While this, and numerous other suggestions are available, one of the key problems is to be able to provide appropriate measurements to achieve any of these particular recommended positions. At present, instruments are lacking for proper measurement of the height, width and other dimensions of the tooth in order to determine the proper midpoint for such placement. Similarly if other recommended positions are desired, they likewise require measurement of the height and width in order to determine where the desire placement position occurs. Accordingly, there is at present a need for a suitable instrument which can be utilized to make the necessary measurements of the perimetric region of the tooth surface, such as the height, width, and other such similar measurements.
While most of the bracket placement is on the facial or buccal surface, these same problems also occur with lingual orthodontic bracket placement. In fact, the problems becomes even more critical when the brackets are lingually positioned.
With regard to the actual placement of the bracket, even if a desired location were to be known, there are few instruments which have been thus far provided for bracket placement. By way of example, U.S. Pat. No. 4,422,849 issued to the inventor of the present invention describes a dental instrument for positioning a lingual orthodontic bracket. The instrument includes a housing on which is positioned an arm that includes a device for releasably holding the orthodontic bracket. A level indicator is used for displaying the extent of inclination of the arm with respect to a predetermined plane, such as the cusp tip or incisor ledge of the tooth. Based upon such desired angle of inclination, the bracket can be placed at a desired lingual position on the tooth.
This concept was extended in U.S. Pat. No. 4,455,137, issued to the inventor of the present invention, which provided the ability to indicate the relative position of the placement arm with respect to a level arm. This gave further capabilities by not just limiting the placement to an angular inclination in a first plane but gave further ability for a broader range of placement positioning capabilities.
These concepts were extended not only with respect to lingual orthodontic bracket placement but even for labial placement in U.S. Pat. No. 4,474,555 issued to the inventor of the present invention. Furthermore, the above patent also provided the concept of not necessarily placing the bracket directly on the immediate tooth surface but spacing the bracket through the use of additional adhesive material whereby the bracket can be placed in spaced relationship from the actual tooth surface in order to provide a more uniform wiring capability for the orthodontic treatment.
Another type of bracket placing device is described in U.S. Pat. No. 3,871,098. In this device, an arm projects from the barrel of a housing and includes a tongue which fits into the center groove of the bracket. A second positioning arm is balanced on top of the tooth and through the use of a plunger, the holding arm retaining the bracket projects forward of the device to press the bracket into position on the tooth surface.
While these and other instruments are available for bracket placement, these instruments only do the actual placement. The problem still exists as to selecting the appropriate position and making the bracket placement at the particular desired position on the tooth surface.
Knowing the actual position at which a bracket is located not only permits an accurate orthodontic treatment, but provides other benefits. For example, knowing the exact location of a particular placement enables the replacement of a missing or lost bracket. It also allows for the change in position of a bracket that is not having the correct effect on tooth movement due to the unique anatomy of the crown or variation of the crown root long axis. It also permits a comparison of bracket placement to tooth movement with similar teeth.
The ability to measure the entire crown surface can also permit a comparison of bracket placement on right and left quadrants of similar teeth. This enables correction to be placed in bracket location due to variations in anatomy. Numerous other benefits are also available once the measurements of the tooth surface can be achieved.
Accordingly, there is a need for a suitable dental instrument which can provide the necessary measurement of the perimetric values of teeth in order to determine the surface area of the teeth, and which can suitably position a dental bracket on either the lingual or labial surface at a desired location based upon such measurement.